Field of the Invention
The present invention relates to a metallic nanostructure synthesis technology, particularly to a one-dimensional titanium nanostructure and a method for fabricating the same.
Description of the Related Art
The current metallic nanostructure synthesis technology includes a photolithographic method, a hard template method, a seed-mediated growth method and a de-alloy method.
In the photolithographic method, a layer of photoresist is coated on a substrate and illuminated by the light filtered by a photomask. The pattern of the photomask reflects incident light. The light passing the photomask has a pattern identical to the pattern of the photomask and selectively exposes the photoresist coated on the substrate, whereby the pattern of the photomask is completely duplicated to the photoresist. After the abovementioned exposing step, the exposed photoresist is developed to reproduce the pattern of the photomask on the photoresist. Then, the photoresist is removed to obtain the desired nanowire. The method has disadvantages of expensive equipment and complicated processes. Further, the wavelength of the laser limits the size of nanowires.
The hard template method uses a polymeric material, a porous template or a biomaterial as the template for growing a special metallic nanostructure. The template is placed on a substrate, and a metallic material is deposited on the template with an electrodeposition method, a PVD (Physical Vapor Deposition) method, or a solution reduction method. Then, the template is removed to obtain a metallic nanostructure. The metallic nanostructure fabricated by the method is likely to have many tumbling defects. The size of the nanostructure is limited by the pore size or line width of the template. Besides, the method needs to fabricate a template beforehand and thus has a very complicated process.
The seed-mediated growth method is a liquid-phase synthesis method using a solution containing a reducing agent and a surfactant. The surfactant is a key factor in the liquid-phase method, not only preventing metallic nanoparticles from agglomeration or precipitation in solution but also facilitating the anisotropic growth of the metallic nanoparticles. The surfactant molecules have a hydrophilic terminal and a hydrophobic terminal and are likely to self-assemble to form micelles having various shapes. The micelles may function as templates to form nanostructures having a special geometrical shape. However, the method has a low yield in the scaled-up process. Besides, the nanostructures fabricated by the method are in form of powder. While the nanostructures are intended to apply to a heat-resistant substrate, the powder must be mixed with some agents to form a paste. Then, the paste is coated on the substrate. However, the mixing-coating process may vary the characteristic of the nanostructures. Besides, the uniformity of the mixing-coating process may affect the performance of the nanostructures.